U.S. patent application number 17/730640 was filed with the patent office on 2022-08-11 for helical device for cooling or heating.
The applicant listed for this patent is Theodore H Gasteyer, III, Yeu-Chuan Simon Ho. Invention is credited to Theodore H Gasteyer, III, Yeu-Chuan Simon Ho.
Application Number | 20220248722 17/730640 |
Document ID | / |
Family ID | 1000006299994 |
Filed Date | 2022-08-11 |
United States Patent
Application |
20220248722 |
Kind Code |
A1 |
Gasteyer, III; Theodore H ;
et al. |
August 11, 2022 |
HELICAL DEVICE FOR COOLING OR HEATING
Abstract
The efficiency of a device for cooling or heating objects on a
belt that moves through a path of a helix, in which gaseous cooling
or heating medium is circulated within the device, is improved by
positioning fans that circulate the cooling or heating medium so
that the fans are distanced from the top of the helix.
Inventors: |
Gasteyer, III; Theodore H;
(Naperville, IL) ; Ho; Yeu-Chuan Simon;
(Naperville, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gasteyer, III; Theodore H
Ho; Yeu-Chuan Simon |
Naperville
Naperville |
IL
IL |
US
US |
|
|
Family ID: |
1000006299994 |
Appl. No.: |
17/730640 |
Filed: |
April 27, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16430567 |
Jun 4, 2019 |
11350650 |
|
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17730640 |
|
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|
62683301 |
Jun 11, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A23L 5/17 20160801; A23L
3/361 20130101; F25D 17/06 20130101; A47J 37/045 20130101; A23V
2002/00 20130101; F25D 13/067 20130101; A47J 27/002 20130101 |
International
Class: |
A23L 3/36 20060101
A23L003/36; A23L 5/10 20060101 A23L005/10; A47J 27/00 20060101
A47J027/00; F25D 13/06 20060101 F25D013/06; F25D 17/06 20060101
F25D017/06; A47J 37/04 20060101 A47J037/04 |
Claims
1. A device useful for cooling or heating objects that pass through
the device, comprising a housing having a bottom, top, and side
walls, which create an enclosed space, and including first and
second openings each of which is present through a side wall
between the enclosed space and the exterior of the housing, an
endless movable belt that extends between the first and second
openings and that follows within the housing a path a portion of
which is in the form of a helix which is oriented vertically around
a vertical central space within the housing and includes a
plurality of tiers of the belt that are arrayed vertically, outlets
within the housing that are capable of dispensing heat transfer
medium into the interior of the housing, one or more than one fan
that is positioned in the vertical central space and that has
blades oriented so as to be capable of impelling gaseous heat
transfer medium vertically through the blades and capable of
impelling movement of gaseous heat transfer medium across the tiers
in the housing, wherein the fan is attached by a drive shaft to a
motor that is capable of rotating the shaft and the fan, and
wherein the fan is positioned in the vertical central space at a
height such that at least one tier of the belt in the helix is
located below the fan and at least one tier of the belt in the
helix is located above the fan; wherein there is circulation space
within the housing between all of the exterior edges of the belt in
the helix and the interior surfaces of the side walls, and between
the topmost tier of the belt and the interior surface of the top
wall, and there are openings between the vertical central space and
the interior edges of the belt in the helix, so that gaseous heat
transfer medium can be impelled by the fan across the upper
surfaces of the tiers of the belt in the helix between the central
space and the circulation space.
2. A device according to claim 1 wherein there is one such fan that
is positioned in the vertical central space.
3. A device according to claim 1 wherein there is no structure
present above the fan that would impede flow of gaseous heat
transfer medium between the central space and the top surfaces of
the tiers of the belt in the helix.
4. A device according to claim 1 wherein there is no structure
present that would prevent flow of gaseous heat transfer medium
between the topmost tier of the belt in the housing and the top
wall of the housing.
5. A device according to claim 2 wherein there is no structure
present above the fan that would impede flow of gaseous heat
transfer medium between the central space and the top surfaces of
the tiers of the belt in the helix.
6. A device according to claim 2 wherein there is no structure
present that would prevent flow of gaseous heat transfer medium
between the topmost tier of the belt in the housing and the top
wall of the housing.
7. A device useful for cooling or heating objects that pass through
the device, comprising a housing having a bottom, top, and side
walls, which create an enclosed space, and including first and
second openings each of which is present through a side wall
between the enclosed space and the exterior of the housing, an
endless movable belt that extends between the first and second
openings and that follows within the housing a path a portion of
which is in the form of a helix which is oriented vertically around
a vertical central space within the housing and includes a
plurality of tiers of the belt that are arrayed vertically, outlets
within the housing that are capable of dispensing heat transfer
medium into the interior of the housing, two fans that are
positioned in the vertical central space and that have blades
oriented so as to be capable of impelling gaseous heat transfer
medium vertically through the blades and capable of impelling
movement of gaseous heat transfer medium across the tiers in the
housing, wherein the fans are attached one above the other to a
common drive shaft that is attached to a motor that is capable of
rotating the shaft and the fans, or to separate drive shafts each
attached to a motor that is capable of rotating the shaft and the
fan, and wherein the fans are positioned in the vertical central
space at heights such that at least one tier of the belt in the
helix is located above the higher fan, and at least one tier of the
belt in the helix is located below the lower fan, and a plurality
of tiers of the belt in the helix are located between the fans;
wherein there is circulation space within the housing between all
of the exterior edges of the belt in the helix and the interior
surfaces of the side walls, and between the topmost tier of the
belt and the interior surface of the top wall, and there are
openings between the vertical central space and the interior edges
of the belt in the helix, so that gaseous heat transfer medium can
be impelled by the fans across the upper surfaces of the tiers of
the belt in the helix between the central space and the circulation
space.
8. A device according to claim 7 wherein there is no structure
present above the fan that would impede flow of gaseous heat
transfer medium between the central space and the top surfaces of
the tiers of the belt in the helix.
9. A device according to claim 7 wherein there is no structure
present that would prevent flow of gaseous heat transfer medium
between the topmost tier of the belt in the housing and the top
wall of the housing.
10. A method for cooling or heating objects, comprising (A)
providing a housing having (1) a bottom, top, and side walls, which
create an enclosed space, and including first and second openings
each of which is present through a side wall between the enclosed
space and the exterior of the housing, (2) an endless movable belt
that extends between the first and second openings and that follows
within the housing a path a portion of which is in the form of a
helix which is oriented vertically around a vertical central space
within the housing and includes a plurality of tiers of the belt
that are arrayed vertically, (3) outlets within the housing that
are capable of dispensing heat transfer medium into the interior of
the housing, and (4) circulation space within the housing between
all of the exterior edges of the belt in the helix and the interior
surfaces of the side walls, and between the topmost tier of the
belt and the interior surface of the top wall, and there are
openings between the vertical central space and the interior edges
of the belt in the helix; (B) operating one or more than one fan
that is positioned in the vertical central space at a height such
that at least one tier of the belt in the helix is located below
the fan and at least one tier of the belt in the helix is located
above the fan, and that has blades oriented so as to be capable of
impelling gaseous heat transfer medium vertically through the
blades and capable of impelling movement of gaseous transfer medium
across the tiers in the housing, to cause gaseous heat transfer
medium to flow from the circulation space to the central opening
between adjacent tiers of the belt in the helix that are on one
side of the fan, and to cause gaseous heat transfer medium to flow
from the central opening to the circulation space between adjacent
tiers of the belt in the helix that are on the other side of the
fan; and (C) moving the belt through the housing with objects on
the belt while dispensing heat transfer medium into the interior of
the housing that chills or heats the objects.
11. A method according to claim 10 wherein the objects comprise
food.
12. A method according to claim 10 wherein one such fan is operated
in step (B).
13. A method for cooling or heating objects, comprising (A)
providing a housing having (1) a bottom, top, and side walls, which
create an enclosed space, and including first and second openings
each of which is present through a side wall between the enclosed
space and the exterior of the housing, (2) an endless movable belt
that extends between the first and second openings and that follows
within the housing a path a portion of which is in the form of a
helix which is oriented vertically around a vertical central space
within the housing and includes a plurality of tiers of the belt
that are arrayed vertically, (3) outlets within the housing that
are capable of dispensing heat transfer medium into the interior of
the housing, and (4) circulation space within the housing between
all of the exterior edges of the belt in the helix and the interior
surfaces of the side walls, and between the topmost tier of the
belt and the interior surface of the top wall, and there are
openings between the vertical central space and the interior edges
of the belt in the helix; (B) operating two fans that are attached
one above the other to a common drive shaft in the vertical central
space at a height such that at least one tier of the belt in the
helix is located above the higher fan, and at least one tier of the
belt in the helix is located below the lower fan, and a plurality
of tiers of the belt are located between the two fans, wherein each
fan has blades oriented so as to be capable of impelling gaseous
heat transfer medium vertically through the blades and capable of
impelling movement of gaseous transfer medium across the tiers in
the housing, to cause gaseous heat transfer medium to flow between
the circulation space and the central opening between adjacent
tiers of the belt in the helix; and (C) moving the belt through the
housing with objects on the belt while dispensing heat transfer
medium into the interior of the housing that chills or heats the
objects.
14. A method according to claim 13 wherein the objects comprise
food.
15. A method according to claim 10 wherein gaseous heat transfer
medium flows through all of the spaces between the central opening
and the circulation space.
16. A method according to claim 11 wherein gaseous heat transfer
medium flows through all of the spaces between the central opening
and the circulation space.
17. A method according to claim 12 wherein gaseous heat transfer
medium flows through all of the spaces between the central opening
and the circulation space.
18. A method according to claim 13 wherein gaseous heat transfer
medium flows through all of the spaces between the central opening
and the circulation space.
19. A method according to claim 14 wherein gaseous heat transfer
medium flows through all of the spaces between the central opening
and the circulation space.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Non-Provisional
application Ser. No. 16/430,567, filed on Jun. 4, 2019, which
claims the benefit of U.S. Provisional Application Ser. No.
62/683,301, filed on Jun. 11, 2018, which is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to devices useful for
effecting rapid heat transfer to or from objects, such as the
cooling and/or freezing or the heating and/or cooking of food or
other products.
BACKGROUND OF THE INVENTION
[0003] Many industries, not least among them the food industry,
find it necessary in the course of their operations to be able to
cool or heat products relatively rapidly.
[0004] When a product needing chilling or freezing is at room
temperature, or is at temperatures higher than room temperature as
the result of a previous processing or cooking step, reducing the
temperature of the product rapidly is desirable in order to
minimize the ability of unwanted physical or chemical changes to
occur. When the product is food, it is highly desirable to avoid
enabling pathological organisms such as bacteria to grow on or in a
product, and (particularly when the product is to be frozen), to
put the product into condition to be packaged prior to its being
stored and/or shipped to distributors or customers. Examples of
products which benefit from this treatment, which are also products
that can be treated by the present invention, include raw foods
such as eggs, hamburger patties, fruits and vegetables, raw or
cooked cuts of meat such as beef, pork, veal, lamb, poultry
carcasses and poultry sections, as well as processed foods prepared
by combining various ingredients, such as pastries, pre-packaged
entrees and complete dinners.
[0005] When a product is to be heated or cooked, the ability to
achieve the necessary heat transfer rapidly is useful in order to
minimize the opportunity for pathogens to grow, and to achieve a
greater rate of processing in a given period of time.
[0006] Many techniques are known for cooling and freezing large
numbers of products such as food products. Examples include
impingement coolers, mechanical refrigerators, and other devices
wherein the product is conveyed through a chamber wherein the
product is exposed to low temperatures for a sufficient period of
time to reduce the temperature of the product to the desired final,
cooled temperature.
[0007] Many techniques are also known for heating and cooking large
numbers of products such as food products, such as tunnel ovens and
the like. One preferred type of device applicable to
cooling/freezing and heating/cooking applications is known as a
spiral or helical cooler or cooker, wherein at least a portion of
the path that the product follows as it is conveyed through a
chamber is in the form of a helix. For example, the product is
placed on a moving flexible belt that follows a path which curves
around on itself as it steadily climbs. With this type of device,
the product travels a longer distance and experiences a longer
dwell time in the cooling or heating environment for a given amount
of area occupied by the device, taking advantage of the vertical
array of the belt.
[0008] Helical (also referred to as spiral) devices have heretofore
presented a drawback that the successive tiers of the belt
interfere with heat transfer from or to the product, because of the
proximity of adjacent tiers which interfere with flow of cooling or
heating air. Also, it has previously been considered necessary to
include baffles and similar structure to guide the flow of the
gaseous heat transfer medium within the unit, but the resulting
tortuous path leads to loss of efficiency and loss of cooling
capacity. The present invention provides devices and methods that
retain the advantages of helical devices but which achieve faster
heat transfer to or from the product than has been available up to
now.
BRIEF SUMMARY OF THE INVENTION
[0009] One aspect of the present invention is a device useful for
cooling or heating objects such as food products that pass through
the device, comprising
a housing having a bottom, top, and side walls, which create an
enclosed space, and including first and second openings each of
which is present through a side wall between the enclosed space and
the exterior of the housing, an endless movable belt that extends
between the first and second openings and that follows within the
housing a path a portion of which is in the form of a helix which
is oriented vertically around a vertical central space within the
housing and includes a plurality of tiers of the belt that are
arrayed vertically, outlets within the housing that are capable of
dispensing heat transfer medium into the interior of the housing, a
fan that is positioned in the vertical central space and that has
blades oriented so as to be capable of impelling gaseous heat
transfer medium vertically through the blades and capable of
impelling movement of gaseous heat transfer medium across the tiers
in the housing,
[0010] wherein the fan is attached by a drive shaft to a motor that
is capable of rotating the shaft and the fan, and wherein the fan
is positioned in the vertical central space at a height such that
at least one tier, and preferably a plurality of tiers, of the belt
in the helix are located below the fan and at least one tier, and
preferably a plurality of tiers, of the belt in the helix are
located above the fan;
wherein there is circulation space within the housing between all
of the exterior edges of the belt in the helix and the interior
surfaces of the side walls, and between the topmost tier of the
belt and the interior surface of the top wall, and there are
openings between the vertical central space and the interior edges
of the belt in the helix, so that gaseous heat transfer medium can
be impelled by the fan across the upper surfaces of the tiers of
the belt in the helix between the central space and the circulation
space.
[0011] In alternate embodiments, there can be more than one such
fan on the shaft.
[0012] In another aspect of the present invention, there is no
structure present that would prevent flow of gaseous heat transfer
medium between the central space and the upper surfaces of any
tiers of the belt in the helix. In yet another aspect of the
present invention, there is no structure present between the
topmost tier of the belt in the housing and the top wall of the
housing.
[0013] Another aspect of the present invention is a method for
cooling or heating objects such as food products, comprising
(A) providing a housing having (1) a bottom, top, and side walls,
which create an enclosed space, and including first and second
openings each of which is present through a side wall between the
enclosed space and the exterior of the housing, (2) an endless
movable belt that extends between the first and second openings and
that follows within the housing a path a portion of which is in the
form of a helix which is oriented vertically around a vertical
central space within the housing and includes a plurality of tiers
of the belt that are arrayed vertically, (3) outlets within the
housing that are capable of dispensing heat transfer medium into
the interior of the housing, and (4) circulation space within the
housing between all of the exterior edges of the belt in the helix
and the interior surfaces of the side walls, and between the
topmost tier of the belt and the interior surface of the top wall,
and there are openings between the vertical central space and the
interior edges of the belt in the helix; (B) operating a fan that
is positioned in the vertical central space at a height such that
at least one tier, and preferably a plurality of tiers, of the belt
in the helix are located below the fan and at least one tier, and
preferably a plurality of tiers, of the belt in the helix are
located above the fan, and that has blades oriented so as to be
capable of impelling gaseous heat transfer medium vertically
through the blades and capable of impelling movement of gaseous
transfer medium across the tiers in the housing, to cause gaseous
heat transfer medium to flow from the circulation space to the
central opening between adjacent tiers of the belt in the helix
that are on one side of the fan, and to cause gaseous heat transfer
medium to flow from the central opening to the circulation space
between adjacent tiers of the belt in the helix that are on the
other side of the fan; and (C) moving the belt through the housing
with objects on the belt while dispensing heat transfer medium into
the interior of the housing that chills or heats the objects.
[0014] Preferred objects include food products, by which is meant
edible products, whether packaged or not packaged. Other objects
with which the invention may be useful include finished articles,
raw metals and ores, powders, and medical products.
[0015] In a preferred embodiment of this method, gaseous heat
transfer medium flows through all of the spaces between the central
opening and the circulation space.
[0016] As used herein, "cooling" and its conjugate forms means
removing heat from an article, and thus encompasses reducing the
temperature of the article, freezing the article, or both reducing
the temperature and freezing.
[0017] As used herein, "heating" and its conjugate forms means
adding heat to an article, and thus encompasses increasing the
temperature of the article, cooking the article, or both increasing
the temperature and cooking.
[0018] As used herein, "vertical" means not only exactly
perpendicular to the earth's surface but also within an angle of up
to 30 degrees, preferably up to 10 degrees, relative to a line that
is exactly perpendicular to the earth's surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view in partial cutaway of a device
with which the present invention is useful.
[0020] FIG. 2 is a cross-sectional view of an embodiment of the
device of FIG. 1.
[0021] FIG. 3 is a cross-sectional view of the embodiment of the
invention of FIG. 1 taken on line 3-3' of FIG. 1.
[0022] FIG. 4 is a cross-sectional view of another embodiment of
the invention.
[0023] FIGS. 5A and 5B are cross-sectional views of embodiments of
the invention employing two fans.
[0024] FIG. 6 is an expanded view of part of the embodiment of FIG.
3.
DETAILED DESCRIPTION OF THE INVENTION
[0025] One embodiment of the type of device with which the present
invention is useful appears in the drawing figures. However, these
illustrations are provided for purposes of description and are not
intended to limit the definition of this invention.
[0026] The device generally comprises unit 10 comprising an
insulated housing 12, and an endless movable belt 24 that carries
products 34 through housing 12. The device also comprises structure
and components, not shown in FIG. 1, for cooling or heating the
products as they pass through the housing 12.
[0027] Housing 12 can take the form of a rectangular parallelepiped
having vertical walls 14, a top wall 16, and a bottom wall 18, all
of which are preferably sealed together and thermally insulated
against heat flow therethrough into or out of the interior of
housing 12. One or more doors 20, and optional window 22, can be
provided to permit physical and visual access to the interior.
Control panel 21, containing controls such as for the operation of
the belt, fan, and any cooling or heating unit associated with the
device, and conveniently also containing gauges for monitoring the
conditions of the unit, can also be provided on the exterior of a
wall 14.
[0028] The products to be cooled or heated are preferably conveyed
on endless belt 24 which can be of known construction. The belt is
preferably porous enough to permit air to flow through it. Examples
include belts of unitary material such as a polymeric web of
material, and belts of interlocked links of polymeric or metallic
material which can flex and change their position relative to
adjacent links so as to accommodate the belt being able to pass
through the straight and curved portions of the belt's route.
Material that serves as gaseous heat transfer medium described
herein (such as chilled air, or cryogenic vapor) passes through
open spaces between the links of this type of belt.
[0029] Loading (or unloading) station 26 is preferably provided
adjacent to a first opening 28 through one wall 14, and an
unloading (or loading) station 30 outside a second opening 32
through the same or another wall 14 is also provided. With these
stations and openings, product can be fed into and recovered from
the unit 10 without the operator needing to enter the unit. The
belt 24 extends between first opening 28 and second opening 30, by
which is meant that a product can be placed onto belt 24 at one of
said openings and removed from belt 24 at the other of said
openings, from outside unit 10. The many ways that products can be
placed onto belt 24 include placing product onto belt 24 by hand,
or by positioning another conveyor outside the unit so that
products can move off the end of the conveyor onto belt 24.
Similarly, products can be removed from belt 24 by hand, or by
being moved off of belt 24 onto another conveyor outside the unit.
Thus, the belt 24 can extend from the interior of the housing 12
through openings 28 and 32 to outside the housing, as shown in FIG.
1, but does not need to.
[0030] As shown in FIG. 1, one of the openings 28 and 32 is located
at a relatively low elevation, such as at about the same level as
the lower end of the helix formed by the belt, and the other of
these openings is at a relatively high level at the upper end of
the helix. Product can pass from low to high, as indicated by the
arrows in FIG. 1, or from high to low. A small number of products
34 are shown in FIG. 1, for purposes of illustration, but in actual
practice the belt could be carrying a much higher number of
products.
[0031] The belt 24 is driven through its path in any manner by
suitable equipment. A preferred type of equipment employs a
cylindrical cage 49 which typically comprises a plurality of
vertical bars 50 which are spaced apart from each so that gaseous
heat transfer medium can flow between the bars. The bars 50 are
arrayed in the form of a cylinder and are attached to circular
rolled angles at the top (shown as 52) and the bottom (shown as
53)) and located around the outermost circumference of central
space 104 (see also FIG. 2) within the helix formed by the helical
portion of the belt. The outer surfaces of the bars 50 of cage 49
frictionally engage the interior edges 24A of the belt 24 in the
helix. The cage 49 is rotated about its longitudinal (vertical)
axis via a motor 54 which is connected by suitable linkage to the
cage, and the rotation of the cage frictionally engages the belt
and causes the belt to move through its path. A fuller description
of this type of equipment appears in U.S. Pat. No. 4,953,365.
[0032] The belt 24 can alternatively be moved through its path by
any other suitable equipment, such as the combination of a roller
or pulley over which the belt passes and that engages the belt
(such as by friction or by engagement of teeth on the roller with
the belt material), and a motor and suitable connecting linkage by
which the motor turns the roller or pulley and thereby causes the
belt to move.
[0033] The path of belt 24 as shown in FIG. 1 extends within the
housing 12 between first opening 28 and then upward about a
generally helical path thereby defining a plurality of tiers 38 and
defining spaces 46 between each pair of adjacent tiers 38. The
tiers 38 are supported by a plurality of horizontal arms 40 which
extend inward transversely and preferably radially inward from
posts 42 that extend between top wall 16 and bottom wall 18.
Circumferential support beams (some of which are shown as 51 and
53) are attached to the inner and outer ends, respectively, of the
arms 40, and have curvature corresponding to that of the inner and
outer edges of the belt 24 so that the inner and outer edges of the
belt are supported by and slide on the upper surfaces of support
beams 51 and 53. Other arrangements for structure that supports the
belt and permits it to move are also known and can be employed, so
long as they support the belt in the desired path and permit it to
move along the path (such as with the aid of rollers or roller bars
on the arms 40). A suitable tensioning mechanism can be provided,
such as is shown at 41, to help the belt to be sufficiently taut
regardless of changes in its length caused by temperature
differentials.
[0034] Referring also to FIG. 2, the housing 12 is dimensioned to
provide lateral circulation spaces 106 between the exterior edges
24B of the belt 24 in the helix and the interior surfaces of walls
14. The housing is furthermore dimensioned to provide top
circulation space 107 between the topmost tier of the belt and the
interior surface of top wall 16.
[0035] The gaseous heat transfer medium is often air. For cooling
purposes, the invention can be practiced using chilled air, or
injected cryogen such as liquid nitrogen or liquid carbon dioxide,
as discussed below. For heating purposes, air can be used as the
heat transfer medium, as can other heat-carrying substances such as
steam. The present invention will be described first with reference
to cooling using air.
[0036] There are several ways that can be employed to cool air for
use in the practice of the present invention. In the embodiment of
the invention shown in FIG. 2, the air within housing 12 is cooled
by cooler 110. Cooler 110 comprises any conventional heat exchange
device by which cooling fluid 112, such as air, passes through
cooler 110 and is fed into housing 12 after having been chilled in
cooler 110 via indirect heat exchange by coming into contact with
piping or other surfaces which are colder than the fluid entering
into cooler 110. One preferred technique is to contact the air with
piping that contains mixed carbon dioxide-ammonia refrigerant,
which is generally at minus 62 degrees F. to minus 63 degrees F.,
so that the air is chilled to about minus 52 degrees F. to minus 53
degrees F. Another preferred technique is to use as the refrigerant
a multicomponent refrigerant such as disclosed in U.S. Pat. No.
6,176,102, which permits the cooling surfaces to have a temperature
even as low as about minus 140 degrees F. so that the air can be
chilled to about minus 125 degrees F.
[0037] Another technique to provide cooling to product in the
device of this invention is to use liquid cryogen such as liquid
nitrogen or liquid carbon dioxide, which are of course very cold
before and after they evaporate. Referring to FIGS. 3 through 6,
liquid cryogen is fed under pressure into the interior of housing
12 via line 192 and is sprayed onto products on belt 24.
Vaporization of the injected cryogen withdraws heat and provides a
very cold gaseous heat transfer medium. Thus, when cryogen vapor is
employed as the cooling medium, cooler 110 is not needed.
[0038] Referring to FIGS. 3, 4, 5A and 5B, (in which, for purposes
of clarity, not all features of the invention may be shown in every
Figure) in one preferred mode of spraying the cryogen one or more
of the arms 40 are hollow and have on the underside a plurality of
nozzles 302 which discharge toward the belt 24. Line 192 from
outside housing 12 is connected to opening 304 in the end of each
arm 40 that is so constructed, and cryogen fed into opening 304
emerges under pressure from nozzles 302 toward and onto the belt
and onto product 34 that is on the belt. Line 192 is connected
outside housing 12 to a tank or other suitable source of cryogen
under pressure.
[0039] If the operator observes that the rate of heat transfer (or
the extent of chilling or freezing) to a belt surface is higher
nearer to an interior edge 24A and less nearer to an exterior edge
24B, then the flows of heat transfer medium out of nozzles 302 can
be varied so that the flow from the nozzles nearer to edge 24A is
less than the flow from the nozzles nearer to edge 24B. Flows can
be varied by using nozzles with different sized openings.
[0040] In embodiments in which products on the belt are to be
heated, the embodiment in FIG. 2 can be employed in which cooler
110 is replaced by an air heater which is a source of heated air
that serves as the heat transfer medium which is circulated and
impinged upon the product. Alternatively, the arrangement in FIGS.
3 through 6 can be employed in which line 192 feeds steam from a
source such as a steam generator, or another high-temperature fluid
from a suitable source thereof, through opening 304 into arms 40
and out nozzles 302. The thus ejected steam or other fluid performs
as a hot heat transfer medium.
[0041] In any of the embodiments of the present invention, an
impeller 100 is present to provide convective heating or cooling.
Impeller 102 is positioned in central space 104 and includes shaft
101 which is attached to motor 44 that, when operating, rotates
shaft 101. While motor 44 is shown in the Figures as located on top
wall 16, the motor 44 that rotates shaft 101 can be situated
elsewhere in the unit and connected via suitable linkages so that
operation of the motor 44 causes shaft 101 to rotate. Shaft 101 can
extend downward from top wall 16, which is also its preferred point
of attachment to motor 44 as shown in FIGS. 2, 3, 4, 5A and 5B. As
can be seen in FIGS. 2, 3, 5A and 5B, shaft 101 can extend downward
from top wall 16 part of the distance toward bottom wall 18, so
that the lower end of shaft 101 is between top wall 16 and bottom
wall 18. However, if desired, as can be seen in FIG. 4, shaft 101
can extend all the way from top wall 16 to bottom wall 18. In
either embodiment, it is preferred to provide one or more bearings
101A which are secured to a wall of the housing 12, such as top
wall 16 and/or bottom wall 18, and/or to structure that is in turn
attached to top wall 16 or bottom wall 18 (such as arm 101B that
appears in FIG. 3). Any such bearings should permit the shaft to
rotate freely within each bearing, and would hold the shaft 101 in
its axial position to restrain it from deviating from its desired
axial position while it rotates.
[0042] One or more fans 102 are attached to shaft 101. Each fan 102
contains one or more blades 103. The fans 102 and blades 103 are
fixed in position so that rotation of shaft 101 causes each fan and
its blades to rotate about the axis of shaft 101. The blades of
each fan 102 (or of one fan 102 when only one fan is present)
should be angled to drive gaseous atmosphere in a vertical
direction from the blades, which is upwards or downwards depending
on the direction of rotation of shaft 101.
[0043] The diameter of the blades 103 inside the central space 104
must of course provide a large enough gap to safely be rotated
without the tips of the blades hitting the interior belt edges 24A
or the inside surfaces of the cage bars for all conditions and
bearing locations. The gap between the tip of each blade 103 and
the belt edges 24A, or the cage bars, whichever is closer to shaft
101, is typically 1 inch or more. This allows for safe operation of
the impeller 100 during operation, even when ice may have built up
on the blades 103 which could change the effective length of a
blade 103 or could cause vibration because of the extra weight that
would be caused by the ice. Shorter blade diameters, even
presenting a gap of up to about 6 inches between the blade tip and
the vertical bars of the cage, have been tested successfully
running at higher rotational speed to provide the same volumetric
flow rate of atmosphere through space 104.
[0044] Each fan 102 is positioned in central space 104 between the
topmost and bottommost tiers 38 of the belt 24 in the helix. When
there is one fan 102 present, one tier 38 (as shown in FIG. 2) or a
plurality of tiers 38 (one example of which is shown in FIG. 4) of
the belt 24 are above the plane of fan 102, and one tier 38 or a
plurality of tiers 38 are below the plane of fan 102. By "plane of
the fan" is meant the horizontal plane, perpendicular to shaft 101,
in which the radial axes of the blades 103 lie. In embodiments
wherein more than one fan is present, such as the embodiments of
FIGS. 5A and 5B in which fans 102A and 102B are present, one tier
38 or a plurality of tiers 38 of the belt 24 are above the plane of
the fan that is closest to the top wall 16, and one tier 38 or a
plurality of tiers 38 of belt 24 are below the plane of the fan
that is closest to the bottom wall 18, and there should also be a
plurality of tiers 38 between the planes of the two fans. More than
two fans may be provided on shaft 101, up to four or five, but one
or two fans are adequate to provide the improved flow and the
improved efficiency that are realized with this invention.
Alternatively, as shown in FIG. 5B, fan 102A is attached to shaft
101 which is driven by motor 44, whereas fan 102B is attached to
another shaft 101B which is driven by motor 44B.
[0045] Rotation of the fan or fans causes gaseous atmosphere on one
side of each of the one or more fans 102 to be drawn across belt
surfaces 24 on each tier from the circulation space 106 into the
central space 104, while causing gaseous atmosphere on the other
side of the fan to be forced across belt surfaces on each tier from
the central space 104 to the circulation space 106. As the gaseous
atmosphere is drawn or forced across each belt surface, the
atmosphere contacts the objects (such as food products) that are on
each such belt surface and cools them (or heats them, depending on
the intended function of the apparatus and on the temperature of
the heat transfer medium relative to the products 34). It will be
understood that whereas the gaseous atmosphere flows in an
essentially vertical direction as it passes through the plane of
the blades 103, the flow of the atmosphere toward the blades and
away from the blades will be not just vertical but also out of the
spaces 46 between each tier 38 of the belt 24 in the helix on the
upstream side of the fan, and into the spaces 46 between each tier
38 of the belt in the helix on the downstream side of the fan. Of
course, the blades are "pitched" by which is meant that the blades
as attached to the fan lie in a plane that is not horizontal and
not vertical but is at an angle relative to the horizontal plane
containing the radius of the blade.
[0046] One flow pattern is illustrated by the large arrows in FIG.
2. In this embodiment, the combination of the direction of rotation
of shaft 101 and the direction in which fan blades 103 are pitched
causes the heat transfer medium to be drawn from circulation spaces
106 into and through the spaces 38 between the tiers of belt 24
that are above the plane of fan 102 (thereby passing across the
surfaces of belt 24 in those spaces and contacting product 34 that
is on those surfaces) as well as through top circulation space 107,
into space 104 above fan 102, then forced downward through fan 102
and into and through the spaces 38 between across the tiers of belt
24 that are below the plane of fan 102 (thereby passing across the
surfaces of belt 24 in those spaces and contacting product 34 that
is on those surfaces), and then into the circulation spaces
106.
[0047] It will be recognized that the direction of flow shown in
FIG. 2 can be reversed, if the direction of rotation of shaft 101
is reversed or if the blades 103 are pitched in the other
direction. Then, the heat transfer medium would be drawn from
circulation spaces 106 into and through the spaces 38 between the
tiers of belt 24 that are below the plane of fan 102 (thereby
passing across the surfaces of belt 24 in those spaces and
contacting product 34 that is on those surfaces), into space 104,
then forced upward through fan 102 and into and through the spaces
38 across the tiers of belt 24 that are above the plane of fan 102
(thereby passing across the surfaces of belt 24 in those spaces and
contacting product 34 that is on those surfaces), as well as
through top circulation space 107, and then into the circulation
spaces 106.
[0048] The positioning of the fan 102 (or multiple fans) can
advantageously be established by reference to the Vertical Stack
Length, which is defined as the vertical distance between the point
at which the belt enters the housing and the vertical distance
between the point at which the belt exits the housing. The bottom
position of the fan blades 103 should be a distance that is at
minimum about 10% of the Vertical Stack Length below the level at
which the belt exits and that is at maximum about 50% of the of the
Vertical Stack Length below the top of the belt stack. Optimally
this fan position should be a distance of between 20% and 40% of
the Vertical Stack Length below the level at which the belt exits
the housing. At distances below the level at which the belt exits
the housing of less than 20% of the Vertical Stack Length, the fan
is so close to the top of the apparatus that there can be high
velocities and high pressure drops on the inlet that lower the
performance and flow rate of the fan, which can reduce the heat
transfer and freezing or heating capacity of the apparatus. At
distances below the level at which the belt exits the housing of
more than 50% of the Vertical Stack Length, the shaft that is
driving the fan can become long enough that it can become difficult
to stabilize at the high rotational speeds that are required to
produce high velocities and flow rates across the tiers.
[0049] The positioning of the fan as described herein enables the
user to operate without any baffles or other structure, above the
topmost tier of the belt other than the top wall itself, that would
completely block flow of gaseous heat transfer medium between the
topmost tier of the belt and the top wall of the housing. The
positioning of the fan as described herein also enables the user to
operate without any baffles or other structure that would prevent
the gaseous atmosphere from passing in either direction into or out
of the space between tiers of the helix, between circulation space
106 and central space 104. However, the user may find it
advantageous to include a modified baffle 120 in the region of
central space 104 that extends from the lowest tier of belt 24 as
far upward as 10 to 15% of the distance from the lowest tier of
belt 24 to the inside surface of top wall 16 of the housing.
Typically this modified baffle 120 extends across the openings
between space 104 and the bottom 1 to 3 tiers of the helix. Such a
baffle should be perforate, that is, not completely impermeable but
having openings (holes or slots) through it to permit some gaseous
atmosphere to pass through it. This is advisable to reduce the
velocity of the atmosphere across the lowest tiers of the belt in
the helix when the product on the belt is relatively light, while
still permitting heat transfer medium to flow across the tiers and
contact products on those tiers.
[0050] In the embodiments of FIGS. 5A and 5B, the blades of the two
fans 102A and 102B are preferably pitched in opposing directions,
although this is not absolutely necessary. When the blades are
pitched in opposing directions, then rotation of shaft 101 in one
direction will cause the heat transfer medium to be drawn from
circulation spaces 106 into and through the spaces 38 between the
tiers of belt 24 that are above the plane of the fan 102B that is
positioned lower on shaft 101 and below the plane of fan 102A that
is positioned higher on shaft 101 (thereby passing across the
surfaces of belt 24 in those spaces and contacting product 34 that
is on those surfaces), into the region of space 104 that is between
the fans, then forced upward through fan 102A and downward through
fan 102B, and into and through the spaces 38 across the tiers of
belt 24 that are above the plane of fan 102A (thereby passing
across the surfaces of belt 24 in those spaces and contacting
product 34 that is on those surfaces), as well as through top
circulation space 107, and into and through the spaces 38 across
the tiers of belt 24 that are below the plane of fan 102B (thereby
passing across the surfaces of belt 24 in those spaces and
contacting product 34 that is on those surfaces), and then into the
circulation spaces 106.
[0051] If the shaft 101 is rotated in the opposite direction, then
the directions of these flows would be reversed. That is, the
gaseous heat transfer medium would be drawn from circulation spaces
106 that are above the plane of fan 102A and those that are below
the plane of fan 102B, across the tiers of belt 24 into space 104
above and below the respective fans, then through fans 102A and
102B into the region of space 104 that is between the planes of
fans 102A and 102B, and then across the tiers that are between the
planes of those fans, into circulation spaces 106.
[0052] Where two fans 102A and 102B are present and their blades
are pitched in the same direction, the overall flow pattern will
resemble that of FIG. 2, in either of two overall patterns: with
flow passing from spaces 106, across the tiers that are above the
plane of the higher fan 102A and into space 104 above the plane of
fan 102A, then through fan 102A and across the tiers that are below
the plane of fan 102A and into spaces 106; or with flow passing
from spaces 106, across the tiers that are below the plane of the
lower fan 102B and into space 104 below the plane of fan 102B, then
through fan 102B and across the tiers that are above the plane of
fan 102B and into spaces 106.
[0053] There are significant variations in the vapor velocities
over the product in a radial flow helical device depending on the
location within the enclosure. A series of measurements were made
at different positions on the belt (inside edge to outside edge)
and different tier heights within the helix. The airflow
measurements in radial flow helical freezers with a fan only at the
very top of the belt stack indicate that a global average velocity
across all tiers of about 325 feet per minute is achieved. When the
fan is in a position according to the present invention and the top
and bottom flow baffles are removed, the global average velocity
measured is raised to 829 feet per minute. This represents a factor
of a 2.55 increase in the velocity of cooling or heating medium
over the products on the belt, and produces a freezer with much
higher capacity for freezing or chilling.
[0054] Computational fluid dynamics (CFD) modeling of the helical
freezer geometry with both the current radial airflow and the
improved radial airflow also indicate a much higher average
velocity is achieved with the lower fan position. The lower
velocities on the inlet of the fan a particularly important to
decreasing the pressure drop across the fan and increasing the flow
through the fan.
[0055] The device of the present invention has numerous advantages
relative to previous designs. Compared to other radial flow
freezers, the new vapor flow pattern is more efficient with a lower
pressure drop that enables lower power to drive the fan, a higher
fan capacity, and higher velocities. Higher average vapor velocity
on the belt surface drives higher levels of convection cooling.
This increased rate of convection enables a higher freezing (or
cooking) capacity in lb/hr in the same available space due to the
better airflow. Other radial flow devices include top baffles to
direct the flow where it is needed, but no top baffles are needed
for the new flow design of the present invention.
[0056] Compared to freezers that employ horizontal flow of the
cooling medium, the present invention provides higher average
velocity for a lower power input. Also, the present invention does
not require a solid center cage or additional baffles to force flow
across the belt surface. All flow on both the inlet and outlet side
of the fan produces velocity across the belt, so there is minimal
wasted velocity that does not pass over the product.
[0057] Compared to freezers that employ vertical flow of the
cooling medium, the present invention requires much lower power
input to produce high gas velocities across the belt. The added
expense and complexity of closing off the belt edges and cage to
flow is not required with the improved flow path of the present
invention.
[0058] Other advantages of the present invention include higher
capacity and smaller equipment size. As the convection cooling is
significantly enhanced, a smaller lower cost freezer will be
required for many users. The absence of any required flow-directing
baffles opens up the freezer to both better airflow and easier
sanitation of the equipment at the end of the production shift.
Additional advantages of the present invention include lower
operating cost per pound of production; lower power requirements
and higher capacity drive a lower cost of operation per unit of
capacity. The advantages of the present invention are especially
pronounced for cryogenically cooled freezers.
[0059] The location of the fan according to the present invention
is between sections of the flow resistance. This allows the flow of
gaseous heat transfer medium on the tiers above the fan position to
be driven by the suction into the fan and the flow on the tiers
below the fan position to be driven by the positive pressure output
of the fan. As a result, there is little or no wasted velocity
produced.
[0060] Dividing the flow resistance into two sections (above and
below the fan) lowers the flow resistance in each section and
products higher velocities. The lower flow resistance results in
lower pressure drop, which produces much higher gas flow rates and
velocities across the product on the belt with the same power
consumed in producing the flow of the gas.
[0061] The overall circuit length of the flows of the gaseous heat
transfer medium is minimized which maximizes the velocity across
the belt for a given horsepower of used to create the gas flow.
When the outlet of the fan pushes the flow at high velocities
across the belt inside to outside below the fan blade, the inlet of
the fan pulls the flow at high velocity from outside to inside
across the belt positioned above the fan blade.
[0062] Also, the present invention employs a much larger effective
inlet flow area to the fan, that reduces pressure drop on the inlet
to the fan.
[0063] The device of the present invention can be used to cool,
freeze, or form a frozen crusted outer surface, on products that
are at room temperature or that are cooler or warmer than room
temperature, especially including products that have just been
cooked or have just been cut from freshly slaughtered animals. It
can be used to warm or cook objects that enter at room temperature
or at temperatures higher or lower than room temperature,
especially including products that are fresh or have been stored in
chilled or frozen conditions.
[0064] The device of the present invention affords numerous
advantages. The principal advantage is a much higher rate of heat
transfer from the product relative to the amount of cryogen
employed. This advantage leads to several other advantages: for a
given size of device, more product can be cooled or heated, and/or
product can be cooled (or heated) to a lower (or higher)
temperature; a given amount of cooling or heating can be achieved
in a much shorter period of time; and a given amount of product can
be cooled or heated more quickly in a smaller unit than heretofore
needed.
[0065] In particular, when this invention is used to freeze at
least the outer surface of a product, the product retains a greater
proportion of its internal moisture compared to freezing using
previously known devices, because other freezing regimens permit a
greater amount of that moisture to be lost from the product before
a frozen outer layer forms that prevents further moisture loss. The
more rapid cooling and freezing and this invention provides
establishes that frozen outer layer much more quickly, thereby
retaining more of the internal moisture. This advantage is
especially useful when the product being treated is warm and/or
moist, such as freshly produced raw-meat, freshly cooked meat, and
freshly steamed or cooked vegetables.
* * * * *